The attorney general’s office contends the feds are obligated under law to undertake such a study because several agencies are part of the Delaware River Basin Commission, which is currently constructing rules for natural gas drilling within the river’s watershed.

“Before any decisions on drilling are made, it is our responsibility to follow the facts and understand the public health and safety effects posed by potential natural gas development,” Schneiderman said in a statement. “The federal government has an obligation to undertake the necessary studies, and as I made clear last month, this office will compel it to do so.”

In a letter sent to Schneiderman and obtained last week by Gannett’s Albany Bureau, U.S. Army Corps of Engineers Division Commander Peter DeLuca said he disagrees with the attorney general’s assessment. DeLuca contends that since the federal government is only one of five entities in the Delaware River Basin Commission – along with New York, Pennsylvania, Delaware and New Jersey – it is not subject to the National Environmental Policy Act as Schneiderman claims.

Several federal agencies participate as part of the commission, with the Army Corps playing a lead role.

The Delaware River basin includes portions of Broome, Delaware, Chenango and Ulster Counties, as well as a large chunk of the New York City watershed. It sits above the gas-rich Marcellus Shale formation.

The commission is currently drafting rules for natural gas drilling and hydraulic fracturing, a process involving the injection of millions of gallons of chemical-laced water to break up shale formations, within the river basin. A public comment period on a draft set regulations wrapped up earlier this year.

The lawsuit will be filed in federal court in Brooklyn, according to Schneiderman’s office.